For the soft physics input to our calculation of pion electroproduction we use the same DAs
and form factors as for \(\pi ^0\)  photoproduction [1]}.
Thus, for the twist-2 pion DA we use the truncated Gegenbauer expansion
\(\phi _\pi (\tau )\,=\,6\tau \bar{\tau }\,\big [1 + a_{2}\;C_2^{3/2}(2\tau -1)\big ]\) 
